CLONING, SEQUENCING AND DEDUCED FUNCTIONS OF A CLUSTER OF STREPTOMYCES GENES PROBABLY ENCODING BIOSYNTHESIS OF THE POLYKETIDE ANTIBIOTIC FRENOLICIN
CLONING, SEQUENCING AND DEDUCED FUNCTIONS OF A CLUSTER OF STREPTOMYCES GENES PROBABLY ENCODING BIOSYNTHESIS OF THE POLYKETIDE ANTIBIOTIC FRENOLICIN
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DOI：
10.1016/0378-1119(94)90351-4
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发表时间：
1994-05-03
期刊：
影响因子：
3.5
通讯作者：
HOPWOOD, DA
中科院分区：
文献类型：
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作者：
BIBB, MJ;SHERMAN, DH;HOPWOOD, DA
从玫瑰黄链霉菌中克隆出一个10.2 kb的DNA片段，该片段含有聚酮合成酶（PKS）编码基因（fr en），该基因被认为是决定抗生素frenolicin和纳米霉素生产的基因。对该DNA的5530bp连续片段进行测序。对该序列进行分析，发现有5个完整的开放阅读框（orf）沿一个方向转录（orf 1、2、3、5、4），而位于ORF3和ORF5之间的一个完整的开放阅读框（ORFX）沿相反方向转录。推断的ORF1、2、3、4和5的氨基酸序列与其他链霉菌中已知的ii型PKS组分的序列非常相似：推测的异二聚体（ORF1+2）酮合酶、酰基载体蛋白、环化酶和酮还原酶。ORF4产物的n端和c端之间的相似性也在其他异色马酮抗生素产生的相应基因中被发现，这表明环化酶编码基因可能是通过复制产生的。ORFX似乎代表了一类功能未知的新基因，不仅存在于fren基因簇中，也存在于链霉菌物种的其他芳香抗生素生物合成基因簇中。frenn - orf1 -5基因编码了一个PKS，该PKS构建了16或18个碳的新生聚酮，而其他已知的例子中固定长度为16和20个碳，这被证明对理解控制聚酮链长度的机制以及还原和环化模式有价值。
A 10.2-kb fragment of DNA from Streptomyces roseofulvus, which contains polyketide synthase(PKS)-encoding genes (fr en) presumed to determine production of the antibiotics frenolicin and the nanaomycins, was cloned. A 5530-bp continuous segment of this DNA was sequenced. Analysis of the sequence revealed five complete open reading frames (ORFs) transcribed in one direction (ORFs 1, 2, 3, 5, 4.) and one (ORFX), located between ORF3 and ORF5, transcribed in the opposite direction. The deduced amino-acid sequences of ORFs 1, 2, 3, 4 and 5 closely resemble the sequences of known Components of the type-II PKS from other Streptomyces species: putative heterodimeric (ORF1+2) ketosynthase, acyl carrier protein, cyclase and ketoreductase, respectively. A resemblance between the N-terminal and C-terminal halves of the ORF4 product - also discovered in the corresponding genes from other isochromanequinone antibiotic producers - suggests a possible origin of the cyclase-encoding gene by duplication. ORFX appears to represent a novel class of genes of unknown function present not only in the fren cluster, but also in other clusters of aromatic antibiotic biosynthetic genes in Streptomyces species. The fren-ORF1-5 genes, encoding a PKS that constructs a nascent polyketide of either 16 or 18 carbons, compared with fixed lengths of 16 and 20 for other available examples, are proving to be valuable for understanding the mechanisms controlling polyketide chain length and patterns of reduction and cyclisation.